spectool: ignore query string in URL. BZ 1337544
When constructing the target filename from the given Source or Patch URL
(sub retrieve), do not include the query string (if present).
Example:
* Before: http://some.url/foo.tgz?arg=123 => ./foo.tgz?arg=123
* After: http://some.url/foo.tgz?arg=123 => ./foo.tgz
Regex explanation:
* 1st group: ([^\/]+?)
* Lazily matches one or more characters that are not a forward slash
* 2nd group: (?:\?.*)?$
* Matches a query string (if any) starting with a question mark,
followed by zero or more characters until the end of string,
without creating a capturing group (the leading ?:)